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Earth-size is not Earth-like: the TED Talk by Dimitar Sasselov
July 27, 2010

Two weeks ago, I gave a talk at TED Global 2010 which was very well received, but caused confusion. I talked about Earth-like planets, which many people would equate to Earth-size and "habitable."

Earth-size and Earth-like is certainly not the same. Take the example of Venus, an Earth-size planet whose surface will melt lead. I understand that the term "Earth-like" was misleading to most of the media coverage. The Kepler mission is designed to discover Earth-size planets but it has not yet discovered any; at this time we have found only planet candidates.

The June 2010 Kepler data release with 306 candidates is an encouraging first step along the road to Kepler's ultimate goals, and specifically - the goal to determine the frequency of Earth-size planets in and near the habitable zone. However, these are candidates, not systems that have been verified sufficiently to be considered true planets. It will take more years of hard work to get to our goal, but we can do it.

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